1. Field of the Invention
This invention relates to a document reading apparatus such as a facsimile machine and a scanner.
2. Description of Related Art
When an apparatus, such as a facsimile machine, which is capable of reading and printing a document, makes a copy of a document by reading a document and printing the read document as it is, a copied image is enlarged or reduced if the resolution for reading a document differs from that for printing a document. To avoid this, resolution conversion is required. Resolution conversion by either a software- or hardware-based method tends to produce moire patterns (a series of light and dark patterns) on a copied image. As a result, the printing quality becomes inferior to that attained in a case where the resolution for reading and that for copying are the same.
Even when the resolution for reading and that for printing are the same, if the reading resolution of the facsimile machine differs from that defined by the communication standards, resolution conversion is required to prevent such a difference of image size because the resolution of the reading apparatus in the main scanning direction (in a direction in which a reading sensor detects an image in one detecting operation) is not changeable.